A new generation of socialization research has begun to exploit the power inherent in designs that compare and contrast the family experiences and unfolding psychological development of siblings growing up in the "same family." The proposed longitudinal study examines the familial conditions underlying gender role socialization in middle childhood, as well as the implications of these family roles, relationships, and activities for children's sex-typed psychological characteristics and general psychosocial functioning, from two distinct angles: (1) a "between family" approach in which children are compared across families that vary in terms of parents' gender roles and the sex composition of the sibling dyad; and (2) a "within family" approach that emphasizes the differential experiences of gender role socialization for two siblings in each family. The sample includes 200 sibling pairs, evenly distributed across the four possible gender composition groups (e.g., older brother, younger sister; older brother, younger brother) and their parents. Older siblings initially will be age 10; younger siblings age 8. Data will be collected at 3 annual points of measurement such that at the third time point younger siblings will be age 10, allowing us to compare siblings' experiences: (1) at the same point in time (when siblings differ in age); and (2) when siblings are at the same age (using data collected at two different times). Data collection at each wave will involve: (1) home interviews with mother, father, older and younger siblings about family relationships, sex-typing, and psychosocial functioning (e.g., perceived competence; school achievement); and (2) a series of 7 evening telephone interviews with both siblings and parents (half with mother, half with father; 5 week days, 2 weekend days) to gather data on specific activities engaged in that day (e.g., participation in household chores; activities with mother vs. father). Hypotheses regarding the connections between family socialization experiences and children's sex-typing and psychosocial adjustment are grounded in four theoretical perspectives: social learning theory, a person-environment fit model, feminist theory, and developmentalists 'notions about the non-shared family environment.